Bumpstart was kind enough to scan the turbo engine section of the series 4 Rx-7 training manual which is basically a Service highlights style document. I'm always on the lookout for random tidbits of information, and I noticed in here that Mazda studied the temperature difference in an oil cooled vs water cooled [presumably stock] turbo:



You can see that with the oil cooled turbo, the temperature of the "metal" (probably the turbo CHRA) shoots up after shutdown and remains more than 100C hotter than the comparable water cooled turbo.

 

I deliberately built my s5 highflow turbo with a non water cooled chra for simplicity reasons.

I also tend towards non water cooled journal bearing turns when buying new. Lets be realistic. They are still going to need overhauls after 60 000 - 100 000 kms anyway.

 

Nice post, but apparently it is beyond the comprehension of the simplistic general public.

 

Very cool little graph to show the difference, definitely makes me glad I'm running water cooled. Garrett posted up a little pdf on water cooled turbos as well and shows a picture of the chra and what they're getting at with the oil coking.

http://www.turbobygarrett.com/turbob...er_Cooling.pdf

You guys have probably seen it but I figure I'll post it anyways, I just liked seeing what was actually happening to the turbo on the inside with the oil residue as I've only taken apart a couple turbos and they were both watercooled.

 

Great info. Simply shows that water cooling is effective and worthwhile.

I don't see the point in not setting up a water cooling system on an aftermarket turbocharger considering our engines already have ports for the lines. Pretty simple setup.

 

For the record, clearly running water cooled is better for the turbo. But I do not currently have an oil cooled turbo on my personal 7. There are a few reasons for this

1) The T04R turbo I have is journal bearing but I would not run a ball bearing turbo without water cooling

2) I don't drive the car much-- 2-3 thousand miles a year, and I change the oil every thousand miles or so

3) I wanted simpler plumbing

4) I got the turbo used and I didn't feel like spending more money (cheap bastard)

5) I am willing to wait a few seconds to cool it down before I shut the engine down, but as the graph above shows that probably has limited effectiveness

6) And MOST IMPORTANTLY... If I am running a turbo blanket and no blowoff valve I might as well abuse the turbo even more I am genuinely curious how long the turbo will last with me doing everything wrong

 

Raymond, I think you meant water cooled turbo.

On turbine engines we use a 2 minute cool down before shutting down the engine.

This is also the orginal purpose for turbo timers. ( driving slowly back through the subdivision for 2 mins. counts also)

Barry

 

yes, I am not running a water cooled turbo currently.

 

My latest personal fd will be fired up next week, running a 67mm ball bearing Garrett(500R). I too will NOT use a BOV, NOT use water/coolant to cool it, WILL use a turbo blanket and likely spray water/meth pre-turbo. In the grand scheme of things the cost of the turbo is really not a big deal when you consider all the other maintenance that goes into these cars if you want to keep them nice.

Great info you posted though. I know a lot of us dont say it enough, but we all appreciate all the info you dig up on these cars/engines. Keep it up.

 

Diamonds are forever.

Turbos are most certainly not. Turbochargers are a consumable

 

More heat is never good, period.
The extent to which it is detrimental may be debatable and may even ultimately be proven to be negligible, but it is undeniable. Choosing not to use water cooling on a turbo AND engine that is already setup for it is just lazy (and cheap). Choosing not to add it on an engine/turbo not set up with such accommodations is a slightly different story.

Thanks for the info! Always enlightening.

 

I wonder how the oil less, water cooled turbos hold up?

 

Does anyone have any experience with the new oil-cooled ball bearing Precision turbos and/or oil cooled BW turbos on the road race course? Precision claims their newest oil/air cooled center sections work well without the water cooling...... I'm not really convinced yet.